Real World Road Rules Challenge: The Ruins is the eighteenth season of the MTV reality television game show, Real World/Road Rules Challenge, and follows The Duel II. The Ruins took place in Phuket, Thailand, with former cast members from MTV's The Real World and Road Rules competing along with several cast members from the Fresh Meat challenge. This season was played in the format of two teams: Champions and Challengers. Players on the Champions team had won at least one previous challenge, while players on the Challengers team had never won a challenge.
This is the last season to use Real World/Road Rules in the on-screen title, before being shortened to The Challenge in the 19th season.
The season premiered on September 30, 2009 and concluded with the "S#!t They Should Have Shown" special on December 23, 2009.